It is known to attach a detachable panel to an aircraft structure using a plurality of fasteners. Countersunk fasteners are frequently used in combination with an anchor nut (fastener receptacle). The anchor nuts are attached to an interior surface of the aircraft structure and the respective countersunk fasteners pass through the panel and the aircraft structure with the countersunk fastener heads substantially flush with the outer aerodynamic surface of the panel.
To reduce parts count it is known to provide a plurality of the anchor nuts as a subassembly arranged on a planar receptacle strip that can be attached to the aircraft structure, e.g. by riveting. On traditional metallic aircraft structures the use of a metallic receptacle strip riveted to the aircraft structure is generally satisfactory.
With the move to greater use of composite materials in aircraft structures, several shortcomings in the use of the metallic receptacle strip have been identified. In particular it is sometimes desirable to provide thickness variation across laminate composite structures (by dropping plies) to better match local load requirements, which results in ramps on the inner surface of the structure generally not found in traditional metallic constructions.